Wednesday 16th January 2013

Time to put some details on Friday's snow forecast.

Before we start - today was what is known as an 'Ice Day' as the maximum temperature was -0.8'C.  Well this is assuming that the temperature doesn't go above 0 between now and midnight which is a pretty safe assumption.

Actually it is worth mentioning a very small risk of a very light snowfall during Thursday, but it should just remain dry.

There is less uncertainty in the snow for Friday, thankfully, than the previous events.

The uncertainty is around how far east the band of snow will travel and where the heaviest will be.

At the moment it looks to start around 7am, and will be generally moderate, sometimes heavy and will last well into Saturday.

Saturday it will be lighter and patchy before dying out.

By the time Saturday morning comes, around 10cm should have fallen.  Before you ask about your area - pretty much the whole of England is included in this forecast, away from the coasts.

I can only say 60% confidence in this specific outcome.  There is a 15% chance of a much heavier snowfall, say 30cm by the end of the weekend, if the band of snow gets stuck over us.  There is also a 15% chance of a much smaller snowfall, say a few cm.  And still a 10% chance of a total disappointment.

Either Sunday or Monday there is another spell but this is much more uncertain as to whether it will be rain, sleet or snow - your guess would be as good as mine right now.

Needless to say it will remain cold - around 0'C by day, and at night between -2'C and possibly as low as -10'C after the snowfall - how cold it gets overnight depends on how clear the sky becomes.

Chance of something milder by Wednesday next week with a thaw thanks to a more normal jetstream pattern - but far from guaranteed.  Any thaw has a good chance of being temporary.